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Tuesday, March 29, 2011

What's All the Fuss About Polyglan? by Dr. Laura Fontana

Polyglcan is a commercially available patented formulation that is labeled for post-surgical joint lavage and joint fluid replacement. This solution is comprised of 3 fractions: hyaluronic acid, sodium chondroitin sulfate, and N-acetyl-D-glucosamine. These 3 fractions are all naturally occurring components of synovia and are instrumental in maintaining joint health. Before discussing the efficacy of this compound, let's review the specific function and independent use of these 3 constituents. Hyaluronan (hyaluronic acid or HA) is a normal joint fluid and cartilage constituent with anti-inflammatory effects as well as joint lubricationand protection properties (1). In equine practice, intra-articular and intravenous administration of HA (Legend) is commonly employed for the treatment of synovitis and osteoarthritis, and intravenous Legend is also used prophylactically. In fact, Legend is the only FDA-approved joint therapy labeled for both intravenous and intra-articular treatment of non-infectious synovitis. Chondroitin sulfate belongs to a class known as polysulfated glycosaminoglycans (PSGAGs), which are an important element of the extracellular matrix of articular (joint) cartilage. Included in this class is Adequan, which is made from cow lung and trachea extracts primarily containing chondroitin sulfate. Adequan and other drugs in this class have been referred to as chondroprotective, or more recently, as slow-acting disease modifying osteoarthritic drugs (SAMOAD) intended to preclude, slow, or revers the cartilaginous lesion of OA (2). Adequan is used intramuscularly, and like HA (Legend), it is also used intra-articularly in equine practice. Glucosamine is a precursor to the disaccharides (sugars) found in aggregan, a molecule that comprises a substantial portion of the extracellular cartilage matrix. Many equine oral joint supplements contain glucosamine as well as chondroitin. The objective of combining hyaluronic acid, chondroitin sulfate, and glucosamine (as Polyglycan), all of which have long been administered independently by a variety of methods, is to create a safe and efficacious product for intravenous and intra-articular use in horse to promote joint health. But, is this combination effective? Frisbie et al (2009) (3) conducted a study to assess intravenous and intra-articular Polyglycan for the treatment of osteoarthritis in horses. The authors concluded that intra-articular Polyglycan (when given once every 7 days for a total of 4 treatments) significantly improved lameness and disease progression in horses, as evidenced by improved lameness scores, decreased radiographic evidence of osteoarthritis, and improved cartilage. In contrast, the intravenous Polyglycan treated horses (which received a dose every 5th day for a total of 14 treatments) showed no improvement in lameness scores and increased radiographic evidence of osteoarthritis. These findings do not support intravenous use of Polyglycan, and suggest that intravenous use may in fact be counterproductive. At this time, and until more studies are performed, continued use of FDA-approved products labeled for intravenous and intra-articular treatment of osteoarthritis is indicated. (1) Frisbie DD, Kawcak CE, McIlwraith CW, et al. Evaluation of polysulfated glycosaminoglycan or sodium hualuronan administered intra-articularly for treatment of horses with experimentally induced osteoarthritis. Am J Vet Res 2009; 70:203 - 209. (2) Section XII, Musculoskeletal System in Equine Surgery 3rd edition. 2005. Jorg Auer and John Stick eds. WB Saunders. Pp 1055 - 73. (3) Frisbie DD, Kawcak CE, McIlwraith CW, Werpy MW. Assessment of intravenous or intra-articular hyaluronic acid, condroitin sulfate and N-acetyl-D-glucosamine in treatment of osteoarthritis using an equine experimental model. Presented at : 55th Annual AAEP Convention; Decemeber 5 - 9: Las Vegas, NV.